This project has characterized cDNAs and genes encoding human and mouse glucose-6-phosphatase (G6Pase), the enzyme deficient in glycogen storage disease (GSD) type 1a. This autosomal recessive disorder is characterized by hypoglycemia, hepatomegaly, growth retardation, lacticacidemia, hyperuricemia, renal dysfunction and hepatic adenomas. Moreover, several human mutations in the G6Pase gene have been identified. These results unequivocally establish the molecular basis of GSD type 1a and open the way for future gene therapy. The cDNA and the gene for mouse liver S- adenosylmethionine (AdoMet) synthetase have also been characterized. The -365 to -2 DNA region upstream of the transcription start site of the AdoMet synthetase gene contains promoter elements and the -518 to -366 DNA region involves negative regulation. The project also showed that pregnancy-specific glycoproteins (PSGs) contain short C-domains which make them secretory proteins, except PSG11w which contains an 81-residue C- domain and is largely retained in cells. By studying the synthesis and processing of PSG, PSG chimeras, and PSG11w deletion mutants in the absence or presence of Brefeldin A, a drug that impedes protein transport from ER to the Golgi system, it was demonstrated that the PSG C-domains specify protein secretion and stability. In addition, the -835 to -34 DNA region upstream of the translation start site of the PSG12 gene was shown to contain both positive and negative elements that control PSG expression and the -172 to -34 DNA region functions as a promoter. The PSG12(-172/- 34) DNA forms four complexes with protein factors in human placental cell extract. Mutagenesis studies have located the core enhancers at nucleotides -148 to -141 and -60 to -55 of the PSG12 promoter. The -156 to -1 DNA region upstream of the transcription start site of the germ-cell alkaline phosphatase (GCAP) gene, which contains three GC-rich nuclear protein binding sites (I, II, and III), directs GCAP expression in choriocarcinoma cells. Site-directed mutagenesis that prevents binding of nuclear proteins to sites I and/or II, results in the loss of factor binding and reduced activator activity. The GCAP promoter that contains an intact binding site III but altered sites I and II has little activator activity, suggesting that protein-protein interaction is important for GCAP gene activation.